Lift Test Research Articles

Investigation of Physical Fitness in Children and Adolescents with Juvenile Idiopathic Arthritis: A Case-Control Study.

Swelling, effusion, tenderness, and pain seen in the joints of juvenile idiopathic arthritis (JIA). This disease may cause limitation in joint movements, muscle weakness, atrophy, balance, and gait disorders. Physical fitness is accepted as an important determinant of health in both childhood and adolescence. The aim was to evaluate the physical fitness of children/adolescents with JIA and compare it with healthy peers. Seventy children/adolescents were included (35 JIA and 35 healthy). The Childhood Health Assessment Questionnaire (CHAQ) and the Brockport physical fitness test battery were used for evaluation. The Brockport physical fitness test battery consists of dominant handgrip strength, curl-up, push-up, trunk lift, shoulder stretch, sit and reach tests, skinfold thickness (calf/triceps/subscapular) measurements, and PACER 20 m test. A significant difference was found in all sub-parameters of CHAQ (P < .05) and dominant hand grip strength (P = .037), curl-up test (P < .001), trunk lift test (P = .018), shoulder stretch (P < .001) and PACER 20 m test (P < .001) tests in favor of the healthy group. Children/adolescents with JIA demonstrated lower performance compared to their healthy peers in muscular and cardiovascular capacity tests (curl-up test, PACER 20 m test, trunk lift test, dominant hand grip strength test, and shoulder stretch test). Their functional abilities are more impaired, and they experience higher levels of pain and lower levels of general well-being compared to healthy peers.

Product Layout Analysis Based on Consumer Purchasing Patterns Using Apriori Algorithm

In every self-service store, it is certain to have a sales transaction data, where the data will continue to grow every day. But in self-service stores the data is only a record of sales at the store. Whereas transaction data can be used as information on how consumer purchasing patterns when shopping at the store, but not all supermarkets know this. So this research aims to find information on these purchasing patterns, where to do this research using the apriori algorithm which is part of the association technique which is also part of data mining, where in its application it will calculate the support value, confindence value and will be tested using the lift ratio. And after the calculation is carried out, optimization will be carried out using the high utility itemset mining variable which will calculate the highest profit value on the product, so that based on the calculation, the final result is obtained with a support value of 85%, a confidence value of 86%, a lift ratio test of 1.01 and the high utility gets the highest result of Rp. 567,000.

Pre-clinical studies comparing the anti-inflammatory potential of artemisinic compounds by targeting NFκB/TNF-α/NLRP3 and Nrf2/TRX pathways in Balb/C mice.

Artemisinin, artemether, artesunate, and dihydroartemisinin are renowned for their antimalarial potential. The current study aims to repurpose the above-mentioned artemisinic compounds (ACs) by conducting an intercomparison to evaluate their antiinflammatory potential (AIP). In order to develop potential candidates for the evaluation of AIP of ACs (50 and 100 mg/kg BW), carbon tetrachloride (1ml/kg body weight (BW)) was administered intraperitoneally to BALB/c mice. Alterations in animal behavior were assessed weekly through tail suspension test, force swim test, open field test, Y-maze test, inverted screen analysis, and weight lifting test. Aberrations in hematological, serological, endogenous antioxidants, and oxidative stress marker profiles were assessed in all twelve groups. Histological alterations were read using hematoxylin and eosin staining. Levels of inflammatory markers including nuclear factor kappa B (NF-κB), tumor necrosis factor alpha (TNF-α), and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), were determined using immunohistochemical analysis (IHCA). Antioxidant markers i.e., nuclear factor erythroid-2-related factor (Nrf-2) and thioredoxin (TRX) were also quantified through IHCA. Comet assay was performed to quantify DNA damage. Oral administration of ACs to mice significantly alleviated the carbon tetrachloride induced inflammation in comparison with silymarin. Reduced levels of several inflammatory markers including nitric oxide, thiobarbituric acid reactive substances, interleukin-1 beta, NF-κB, TNF-α, and NLRP3, underscore the substantial AIP of ACs. IHCA depicted the revitalized percent relative expression of Nrf-2 and TRX in groups treated with ACs. Behavioral analysis revealed that ACs-treated groups significantly (p<0.05) attenuated the memory deficit, anxiety, and depressive-like behavior. Moreover, histopathological, hematological, serological, and endogenous antioxidant profiles indicated substantial AIP of ACs. Findings of comet assay further bolstered the compelling evidence as DNA damage was significantly (p<0.05) curbed down after ACs (100 mg/kg) treatment. All these outcomes implied that ACs exhibited AIP in a dose-dependent manner with maximal AIP imparted by artemisinin (100 mg/kg). This pre-clinical investigation avers the tremendous AIP of ACs targeting key molecular pathways. The current study divulges artemisinin as the most potent antiinflammatory agent among the tested compounds.

Prediction of Conveying Resistance for a Novel Hydraulic-mechanical Hybrid Vertical Lifting System

Objective: Recently a novel hydraulic-mechanical hybrid vertical lifting system was proposed for deep-sea mining. Accurate prediction of conveying resistance is important for the engineering design of the system. Plug flow of coarse particles is the main flow regime in the system. So far rare attention has been paid to the pressure drop prediction of plug flow of coarse particles. This paper aims to investigate eight theoretical pressure drop models on the applicability to predict the pressure drop of plug flow. Methods: Eight theoretical pressure drop models were studied. In addition, a hydraulic-mechanical hybrid vertical lifting test setup was developed. The novelty of this experimental work is that plug flow of coarse particles is formed and the lifting force of the plug can be measured with the test setup. Tests were conducted with varying particle sizes, lifting speeds and plug weights. The particle size is varied among 13, 18, and 25mm. The lifting speed is varied from 0.02m/s to 0.1m/s. The plug weight varies from 5 to 10kg. The range of Reynolds number for the tested particles is between 208 and 2,000. Results: Prediction errors of eight pressure drop models are derived and compared with the experimental data collected during this study. It was found that similar prediction trends are observed for all pressure drop models under most test conditions. Except the Rose model, all models produce average prediction errors less than 15%. The average prediction error for the Rose model is 20.59%. The average prediction error for the Ergun model is 12.43%. Conclusion: From this study it can be seen that the Ergun model produces the smallest prediction error among the eight selected pressure drop models for the given experimental conditions. Therefore, the Ergun model is considered to be most applicable for the calculation of the conveying resistance for the proposed vertical lifting system.

Using vibration to attenuate the adhesive friction behavior between screw conveyor blades and wet coal particles

Screw conveyors are widely used in the transportation of materials in the mining field. The characteristics of material the water content and material shape differences make it different from other powdery and other uniform particle adhesion and friction phenomena, which affects the conveying performance. In order to improve the capability of conveying particles, this paper adds the consideration of vibration factors on the basis of the existing particle lifting test, aiming to study the adhesion and friction mechanism of multi-shaped wet particles under the influence of vibration, and to determine the work parameter that can help improve the conveying performance. The trajectory of microscopic particles under radial and axial vibration conditions, the wear amount of particles on blades and the statistics of particle adhesion and friction intensity are analyzed by discrete element method. The test results show that the adhesion strength of wet coal particles will increase with the increase of water content, and vibration can reduce its adhesion and friction characteristics, and the impact of amplitude and frequency changes is different. The improvement of the amplitude and frequency of the axial vibration of the screw blade can improve the wet coal conveying rate and reduce the wear of the blade. In radial vibration, the transportation rate of wet coal first increases and then decreases with the increase of the amplitude, but the wear amount gradually increases and causes adhesion phenomenon. The transportation rate increases with the increase of frequency, but the wear amount first decreases after increasing. The direction of the radial vibration has an effect on the wear and has little effect on the transportation rate. These results can provide guidance for reducing the adhesion of wet particles and improving the conveying rate in screw conveying.

Research and application on intelligent monitoring and early warning system for Inner-Suspended gin poles

The pressure of the inner suspension pole body is one of the key control indicators that need to be focused on in the design and use of the pole. A real-time intelligent monitoring and early warning system for the working status of the internal suspension pole tower is developed to address safety issues such as excessive inclination, excessive force on the stay wire or support rope during the construction process, including pole body pressure monitoring. The system monitors the axial pressure and inclination angle of the pole body using an integrated sensor for the axial pressure and inclination angle of the pole body. The tension sensor monitors the tension of the lifting, pulling, and supporting ropes, and the anemometer monitors the environmental wind speed. The monitoring data is fed back to the monitoring system through a wireless transmission module, and the safety of the pole state is determined in real-time through an embedded algorithm. When the preset threshold is exceeded, an audible and visual warning is issued. A comparison was made between the actual lifting test and theoretical calculation values, and engineering applications were completed.

A High Lift Test System Based on Wing Deformation

In the existing ground verification test of the high lift system, the flap and slat support structure and transmission system support structure are firmly connected with the fixed test platform, which cannot simulate the effect of real wing deformation on the high lift system. In this paper, a series of lifting devices are used to replace the flap and slat structure and transmission shaft mounting surface on the real wing. Through the position control of the lifting devices, the position change of the mounting surface can be realized, which can better simulate the influence of the real wing deformation on the high lift system.

FMS 기능성 동작훈련이 중국 대학 에어로빅 선수의 신체자세 조절 능력에 미치는 영향에 관한 실험적 연구

The present study explores the effects of FMS functional movement training on aerobic athletes' body posture coordination, and explores the application of FMS functional movement training to the promotion of aerobic athletes' physical performance. In aerobic exercise, body posture control ability is an important criterion for the expression of technical movements, the display of form art aesthetics, and the evaluation of aerobic competition performance. Physical training is the most basic way to improve body posture control, and FMS functional movement training is an emerging physical training mode in recent years, which attaches more importance to functional training than traditional physical training, does not improve athletes' self-confidence in a purposeful way, and has a relatively good improvement effect on technical movements with relatively high movement requirements.40 college aerobic athletes were randomly divided into two groups: Traditional physical training Group (T, N=20) and FMS functional movement training Group (F, N=20). The control group adopts the traditional physical training method, and the functional training group adopts the training method based on the functional movement design of FMS. The results showed that compared with before training, after the traditional physical training group and the FMS functional movement training group intervened, the subjects' FMS test improved significantly in all six motility movements (P&lt;0.05), but there was no significant difference in the straight bow squat and active orthogonal lifting test (P&gt;0.05). The body posture coordination in the dynamic movement and static movement of aerobics was significantly improved only in the FMS functional movement training group (P&lt;0.05).Conclusion: FMS functional training can relatively well promote aerobic athletes' body control ability and body posture coordination in the movement process, which is suitable for further application and dissemination in the physical fitness training of college aerobic athletes.After 12 weeks of training, the scores of various indicators of the experimental group were significantly higher than those of the control group before the experiment, and the results of the FMS test were significantly improved; the effect of the experimental group was better than that of the control group, reducing the incidence of exercise damage; the physical stability, flexibility and asymmetry of the experimental group athletes were improved, but the effect on active right angle rise and straight lunge squat was not obvious. In the body posture control ability test under the static movement plane change condition, the 8-step ventral bridge, 5-step lateral bridge and hexagonal bridge of the experimental group and the control group showed significant differences, and the experimental configuration results were better than the control group, and the before-and-after comparison of the experimental group was significant.It shows that FMS functional movement training can improve the body posture control ability of aerobic athletes in the static movement plane. In the test of aerobic athletes' body posture control ability under the condition of dynamic movement direction change, the results show that the improvement effect of the T-shaped, W-shaped and Y-shaped tests of aerobic combination steps of the experimental group before and after the experiment is better than that of the control group, and each indicator has a significant difference within the group, indicating that FMS functional movement training has improved the body posture control ability of aerobic athletes.

Pengaruh Modifikasi Latihan Model Superman Terhadap Peningkatan Daya Tahan Otot Punggung

This research aims to determine the increase in back muscle endurance. The research method used is pre-experimental design. The test instrument used is the back lift test. The research location was held at SSB Bhineka Futsal, Majenang District, Cilacap Regency with a total of 40 students for two research groups. This research shows the following results: 1. Superman training has a significant impact on increasing back muscle endurance in SSB Bhineka Futsal students, Majenang District, Cilacap Regency. 2. The alternating superman exercise affects increasing the back muscle endurance of SSB Bhineka Futsal students, Majenang District, Regency. 3. SSB Bhineka Futsal students from Majenang District, Cilacap Regency showed a significant increase in back muscle endurance which is different from alternating superman training compared to superman training. Conclusion: SSB Bhineka Futsal students from Majenang District, Cilacap Regency showed an increase in back muscle endurance after doing superman training and superman alternation.

A COMPREHENSIVE AND PROSPECTIVE ANALYSIS TO IMPROVE PATIENT OUTCOMES IN POSTOPERATIVE PERIOD BY OPTIMIZING NEOSTIGMINE DOSE AND TIMING WITH THE HELP OF TOF MONITORING

Objective: The objective is to find out the optimum neuromuscular reversal strategy using Train-of-Four (TOF) monitoring in the postoperative period for complete and risk-free recovery without residual paralysis. In this study, the neuromuscular blockade brought on by cisatracurium will be reversed using a neuromuscular monitor (TOF) and neostigmine administered at the best possible time and dose. In addition, we'll look at the prevalence of neuromuscular paralysis that persists after general anesthesia, as some research have revealed that paralysis may worsen and return once patients leave the recovery area. Methods: A comprehensive prospective, randomized, double-blind and prospective analysis was conducted involving various study groups. Demographic data, residual neuromuscular weakness, negative head lift tests, and Visual Analog Scale (VAS) scores were assessed. TOF monitoring was used regularly to tailor neuromuscular reversal strategies. Results: Incidence of regression of TOF ratio&lt;0.9 and incidence of negative head lift test after extubation among different groups were statistically non-significant by Chi square test at 15 min (p value 0.4), 30 min (0.8) and 60 min (p value 0.9). It also concludes that neuromuscular stimulation given for TOF monitoring is well tolerated by different group of the population in terms of VAS score (mean 3.9, ranging from 3.3 to 3.8). Conclusion: This research suggests that tailoring strategies of neostigmine dose and time of its administration according to TOF ratio leads to complete recovery of neuromuscular function with all the doses (20/30/40 micrograms/kg). This study emphasizes the use of neuromuscular monitoring guided reversal methods to attain complete recovery without residual paralysis.

High Physical Exposure During Female Recruits' Basic Military Training inSweden-A Descriptive Study.

There is a knowledge gap concerning the occurrence of physical complaints/injuries, i.e., musculoskeletal disorders (MSD), among Swedish women who undergo basic military training (BMT). The aims were to describe prevalence and factors related to MSD and explore physical exposure and performance in Swedish female recruits during BMT. A total of 144 females (mean age 22 years) who underwent BMT in 2016 participated in this cross-sectional study. Data regarding self-reported MSD, physical performance, physical activity and exercise, motivation and mental and physical preparation, and physical exposure during BMT and perceived health were collected at the end of BMT through the Musculoskeletal Screening Protocol questionnaire. Additional data on muscle strength were retrieved from IsoKai isokinetic lift tests. Descriptive and analytic (paired samples t-test and logistic binary regression) statistics were used. The prevalence of MSD was high, with 33% (n = 48) reporting MSD before BMT, 78% (n = 113) during, and 50% (n = 72) at the end of BMT. Knee and upper back were the most frequently reported MSD locations. Forty-four (30%) participants felt insufficiently physically prepared for BMT. The physical exposure was high with loaded marches/runs and carrying heavy loads as the most demanding tasks. The longest walking distance was reportedly 55 km, and the reported maximum load was 50 kg. Forty-five participants (31%) had carried a load representing over 50% of their body weight. Most participants reported good to excellent health at the end of BMT. There was a small (8 N) but significant (P = 0.045) increase in mean force over time. Two variables, MSD before BMT (odds ratio 2.24, P = 0.03) and being physically unprepared (odds ratio 3.03, P < 0.01), were associated with MSD at the end of BMT. This study showed that the prevalence of MSD in Swedish female recruits was high before, during, and at the end of BMT, with knee and upper back as the most frequent locations. Although the physical exposure during BMT was occasionally high, self-rated health was mainly perceived as good to excellent at the end of BMT. Previous MSD and being physically unprepared were related to MSD at the end of BMT. These important and relevant findings indicate the necessity for implementing interventions to increase physical fitness and treat MSD at the beginning of BMT.

Level of Physical Fitness Athletics of SMA Negeri 8 Rejang Lebong During the Covid 19 Pandemic

This study aims to determine the level of physical fitness at SMA Negeri 8 Rejang Lebong during the Covid-19 Pandemic. This type of research is descriptive quantitative research. The research sample amounted to 30 people. The instrument used in this study was the TKJI test which consisted of: 60 meter running test, body lift test (30 seconds pi, 60 seconds pa), 60 seconds lying down test, vertical jump test and long distance test (1000 mpi, 1,200 mpa). The classification for the results of the Overall Physical Fitness Test conducted by Boys and Girls was concluded that the Physical Fitness Test at SMA Negeri 8 Rejang Lebong conducted by 20 male students and 10 female students was in the medium category, namely as many as 21 students or with a percentage of 70%.

Correlation between Physical Fitness and Concentration of Gymnastics Athletes

The purpose of the study was to examine the correlation between physical fitness and the concentration of West Java gymnastics athletes. The method used in this research was descriptive quantitative method with correlational design. The sampling technique used in this study was purposive sampling, involving seventeen young athletes (9 women and 8 men; age 19.71 ± 4.22 years, height 1.57 ± 0.07 m, body mass 52.4 ± 7 .58 kg) who were members of PPLP (Student Sport Education and Training Center) and Pelatda (Regional Training Center). The instruments used in this study were a physical condition test (sit and reach test, trunk lift test, standing stork test, whole body reaction, hurdle jump test, 12 core stability test, and beep test) for physical fitness and a concentration grid test for measuring concentration ability. The data processing and analysis results found a correlation of (r = 0.50 with a p-value of 0.0410.05) and a coefficient of determination of 25%. It concludes that there is a correlation between physical fitness and the concentration of West Java gymnastic athletes. Physical fitness is a crucial aspect for an athlete to meet the needs of movement and to perform optimal gymnastic movements without feeling excessive tired, so that they can maintain concentration when practicing or competing. Therefore, activities that can improve physical fitness are considered beneficial in increasing concentration abilities.

A Novel Soft Actuator: MISA and Its Application on the Biomimetic Robotic Arm

This letter presents the design and development of a novel compact motor-based non-linear stiffness soft actuator used for tendon-driven joints, i.e. a magnet-integrated soft actuator (MISA). By applying a pair of antagonistic MISAs to a joint, it is capable of achieving joint stiffness adjustment and joint torque adaptation. The joint with MISAs can achieve a wide range of joint stiffness, about 520% of that obtained by linear stiffness actuators, i.e. LSSA (share the same allowable elastic force and elastic travel with MISA). A stiffness range of 0-121.86 Nm and deflection of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm 8.9\mathrm{^{\circ }}$</tex-math></inline-formula> can be achieved when MISAs are applied to a joint with a moment arm of 180 mm. The MISA achieves a high Power/Volume ratio of 345.02 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\times\, 10^{3}$</tex-math></inline-formula> W/m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> . The application of the MISA in the development of a biomimetic robotic arm is also presented, with the investigation of joint stability and output torque analyse under various joint stiffnesses. Two experiments show that joints with MISAs can emulate the state of human joints when the muscles are tensed and relaxed. The dumbbell lifting test illustrates that the MISAs are capable of actuating the robot with desirable performance.

Physical Fitness Level of Kosgoro Lawang Vocational High School Students After the Covid 19 Pandemic

The Covid 19 pandemic has begun to gradually recover, the condition for approximately 3 years this many stay at home activities have an impact on everyone's fitness, especially for students. on. so it is necessary to measure the level of physical fitness of the students of SMK Kosgoro Lawang by using the Indonesian Physical Fitness Test (TKJI) instrument for the students of SMK Kosgoro Lawang. Research data collection was carried out at SMK Kosgoro Lawang. The data collection technique was carried out through the stages of tests and measurements using (TKJI). The data analysis technique used is descriptive statistical technique. Calculating the Average Value (Mean), using a quantitative descriptive analysis technique with a percentage score. The results of data analysis that have been obtained show that the level of physical fitness of SMK Kosgoro Lawang students on the 60 meter running test is included in the Less criteria with 24%, 64% sufficient criteria and 12% good criteria. On the body lift test, 48% of the criteria are sufficient and 52% good. Furthermore, for the lying down test in the good category 24% and very good 76%. For the vertical jump test in the less than 20% category, 60 is enough, 16% is good and 4% is very good. The 1200 meter run test item, 4% less category, 8% less, 40% enough and 48% good.

Numerical computational fluid dynamics (CFD) simulation study based on plunger gas lift test

In order to explore the feasibility of the Computational Fluid Dynamics (CFD) method for plunger gas lift and the flow pattern in a long wellbore, a lab simulation test was conducted to verify the reliability of the CFD simulation results. Verification data were provided for CFD simulation through carrying out a plunger gas lift lab test for vertical wells, identifying the plunger movement patterns and delivery rates under different flow pressures, and determining the minimum plunger startup pressure or differential pressure and leakage, and an identical CFD physical model was created on the basis of the lab test model, CFD dynamic grid programming and CFD simulation were conducted under test conditions, and a comparison of the simulation and test results was made to identify the calculation accuracy and the rationality of the CFD model and method; finally, boundary conditions such as temperature and pressure were set according to the actual long wellbore (200 m) conditions, the CFD simulation was performed, and the impacts of the downhole conditions on the gas lift performance were analyzed, so as to develop CFD calculation methods to predict the bottom-hole flow pressure, plunger speed, and delivery rate. The results show: the average plunger speed range is 7.74–22.5 m/s when the flow pressure varies from 199.77 to 632.93 kPa, and the leakage rate increases in a nearly linear way with the speed; compared with the lab test results, the simulation results from the created dynamic grid model and multi-phase turbulent flow model have the leakage error of 7.2% and the plunger speed average error is smaller than 11.1%; under long-wellbore conditions, the plunger lift speed shows the change pattern of increasing and then decreasing, the wellbore pressure has a wave-like drop, and in addition to this pressure drop characteristic, the fact that the plunger startup pressure differential increases with the wellhead pressure should be considered (when the bottom-hole pressure is 15 MPa, the wellhead pressure must not exceed 10 MPa).

ÍNDICES DE APTIDÃO FÍSICA NOS ATLETAS DE GINÁSTICA RÍTMICA

ABSTRACT Introduction: Rhythmic gymnastics uses the body as a tool for expression and choreographed beauty. Athletes use various body movements and beautiful voices to create a competitive sport that combines technology and art. This high-level sports performance set results from much targeted fitness training. Yet, the sport lacks research relating fitness to the difficulties of the new rules. Objective: This paper explores the choreographic differences in rhythmic gymnastics under the current rules. The differences in athletes’ body fitness are also evaluated. Methods: The fitness indices of 120 rhythmic gymnasts were evaluated by a developed method encompassing the upper body, trunk and lower limbs. A general analysis of the movement organization characteristics of Chinese rhythmic gymnasts was also performed. Armed with these data, the mathematical statistics method was adopted to conduct empirical research. results: The 10-second long jump, standing jump, lifting, plank, and other 10-s performances in elite athletes were significantly more expressive than those in ordinary athletes (P&lt;0.01). In the lifting test, elite athletes were significantly better than ordinary athletes (P&lt;0.01). There was a significant difference between elite and ordinary athletes in the plank stand (P&lt;0.05). There was no significant difference in the remaining individual scores. Conclusion: The critical period of the upper limb development of rhythmic gymnasts is significantly lagged compared to the lower limbs. The artistic arrangement of rhythmic gymnastics is fundamental to its good presentation. The innovations and diversified changes evidenced an advance in rhythmic gymnastics that athletes must absorb to achieve better competitive results. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Quantifying the Effectiveness of Advertising: A Bootstrap Proportion Test for Brand Lift Testing

Quantifying the Effectiveness of Advertising: A Bootstrap Proportion Test for Brand Lift Testing

Determination Method of Core Parameters for the Mechanical Classification Simulation of Thin-Skinned Walnuts

Simulation can be used to visualize the mechanical classification of walnuts. It can collect microscopic information about walnuts in the classification roller and guide its optimization design. In this process, simulation parameters are essential factors that ensure the effectiveness of the simulation. In this study, the crucial parameters of thin-skinned walnut particles in classification simulation were determined by combining the discrete element method (DEM) and physical tests. Firstly, the moisture content, shear modulus, stacking angle, and some contact parameters in the shell and kernel were obtained by drying test, compression test, cylinder lifting test, and physical test of contact parameters, respectively. A walnut model was constructed using reverse modeling technology. Then, the ranges of the rest contact parameters were determined using simulation inversion based on the Generic EDEM Material Model database. Second, the parameters significantly influencing the stacking angle were screened via the Plackett–Burman test using contact parameters as factors and stacking angle as the index. The results revealed that the walnut–walnut static friction coefficient, walnut–walnut rolling friction coefficient, and walnut–steel plate static friction coefficient significantly affect the stacking angle. The steepest ascent experiment produced the optimal value intervals of crucial parameters. Besides, a quadratic regression model of important parameters was built using the Box–Behnken test to achieve the optimal parameter combination. The stacking and classification experiments verified that the stacking angle and morphology are mostly similar under calibration parameters without any considerable differences. The relative error was only 0.068%. Notably, the relative error of the average staying time of walnut in the classification roller was 0.671%, and the dimensionless distribution curves of stay time were consistent. This study provides technological support to the simulation analysis of walnut classification and recommends novel methods and references to determine the parameters of other shell materials.

Experimental and Numerical Studies on the Effect of Airflow Separation Suppression on Aerodynamic Performance of a Ducted Coaxial Propeller in Hovering

The ducted coaxial propeller (DCP) has great application value in eVTOL aircraft because of its high safety, compactness, and low noise. A numerical simulation method for the DCP is established using the sliding mesh technique. A DCP was designed and manufactured for the lift and power test to verify the numerical method. The characteristics of airflow separation inside the DCP were studied, and the influence of the vortex restrain ring (VRR) on the suppression of airflow separation and on lift augmentation of the duct is analyzed. Results show that, when the tip clearance ratio increases from 0.336% to 1.342%, both the total lift and aerodynamic efficiency decrease by about 11.3%. The influence is mainly reflected in the formation of the tip vortex, airflow separation in the straight, and diffusion sections of the duct. Tip vortex and airflow separation increases DCP energy dissipation and clogs the inner wall of the duct, reducing the effective inner diameter and airflow through the duct. Moreover, the role of the duct is weakened, and the wake is contracted, which increases the induced power loss. By adding a VRR to the diffusion section, the tip vortex and airflow separation can be effectively suppressed, which can increase the aerodynamic efficiency by 5.1%.